Sterilized storage container

ABSTRACT

A container lid (12) is held open by a support plate (18) carrying a chamber (20) which expands at a predetermined point in a sterilizing cycle to react against the lid, moving the plate outwardly to permit the lid to drop onto the container base. A resilient gasket (16) prevents fluid flow into the container after the lid is fallen, but permits fluid flow outwardly past the gasket when interior pressure exceeds exterior pressure. When the container is to be opened, a relief valve (60) relieves the vacuum within the container and filters air entering the container at that time.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 115,678,filed Jan. 28, 1980 now abandoned.

This application is a continuation-in-part of U.S. patent application,Ser. No. 895,239, filed Apr. 10, 1978, which issued as U.S. Pat. No.4,247,517 on Jan. 27, 1981 which is a continuation-in-part of U.S.patent application, Ser. No. 821,042, filed Aug. 1, 1977 which issued asU.S. Pat. No. 4,251,482 on Feb. 17, 1981, which is acontinuation-in-part of U.S. patent application, Ser. No. 734,228, filedOct. 20, 1976, which was abandoned in favor of continuation application,Ser. No. 923,359, filed July 10, 1978 which is now abandoned in favor ofcontinuation application Ser. No. 144,068, filed Apr. 28, 1980,application 734,228 being a continuation-in-part of U.S. patentapplication, Ser. No. 703,044, filed July 6, 1976 which issued as U.S.Pat. No. 4,196,166 on Apr. 1, 1980, which is a continuation-in-part ofU.S. application, Ser. No. 640,824, filed Dec. 15, 1975, which wasabandoned in favor of continuation application, Ser. No. 827,992, filedAug. 26, 1977 which issued as U.S. Pat. No. 4,149,650 on Apr. 17, 1979.

BACKGROUND OF THE INVENTION

This invention relates to an improved system for storing items whilethey are being sterilized, while they are being stored awaiting use,while they are in the process of being used, and after they have beenused and are waiting resterilization. The invention particularly relatesto a system having an improved actuator for automatically releasing acontainer lid at a predetermined temperature, an improved gasket for thecontainer and an improved relief valve for the container. The system isparticularly useful in connection with the sterilization and storage ofmedical items, such as surgical instruments.

As explained in the above-referenced patent applications, a need existsfor an improved system for sterilizing surgical instruments and othermedical items in that the common method of wrapping articles in sheets,sterilizing them and then storing them while still in the sheets, is anunsatisfactory approach. Scientific studies have shown that thirtypercent of the packs prepared with sheets are contaminated by bacteriaat the time of use. Further, instruments in such packs using sheets arecontaminated with lint.

In the most recently filed patent application referred to above,articles to be sterilized are placed in a container, and the containeris placed in an autoclave with the lid held open. After the articleshave been sterilized, a pressure responsive actuator automaticallyreleases the lid and allows it to fall into a closed position wherein aresilient gasket prevents further flow into the container. The actuatorutilizes an expandable chamber which responds to pressure changes toproduce an actuating movement. In a preferred approach, a quantity ofsterilizing fluid is captured within the chamber by means of atemperature responsive valve. Although the systems disclosed in theearlier applications are valuable approaches, further improvements havebeen made in connection with a production version of the system.

SUMMARY OF THE INVENTION

A support plate is mounted on the periphery of a container base, and aprojection or other support means on the support plate holds the lid inopen position. A bellows or other suitable expandable chamber is mountedon the support plate; and at the end of the sterilizing phase of theautoclave cycle a chamber expands against the lid to force the supportmeans away from the lid and allow it to fall onto the base.Advantageously, the support plate may be molded as a one-piece,relatively stiff plastic member, with means on its lower end formounting on the periphery of the container base. In a preferredapproach, the support plate has a pair of projections which extendbeneath the edge of the lid to hold it in open position. A thindiaphragm in the form of a bellows construction is secured to the plateso that the diaphragm in combination with the plate uniquely forms theexpandable chamber. Further, the support plate is provided with an inletnipple that extends into the expandable chamber to permit steam or othersterilizing fluid to enter the chamber during the sterilizing phase ofthe autoclave cycle. A heat shrinkable sleeve valve element surroundsthe nipple to close the chamber during the sterilizing phase to capturea volume of fluid in the chamber.

As the lid falls onto the base, it is critical that a seal be providedto prevent further flow into the container. A resilient gasket carriedby the lid is formed with a lower flap having a feathered edge whichengages a mating surface in the base to provide this initial seal. As avacuum is formed in the container either by a final vacuum in anautoclave cycle or by the cooling of the residual environment in thecontainer, the gasket is further compressed between the lid and thebase. An enlarged bead on the gasket is compressed between the lid andthe base to form a second seal for the container. Thus the containercontents are sealed and preserved in a sterile, lint-free environment.

Because of the excellence of the seal obtained with the gasket, a vacuumis maintained in the container for an extended period of time.Consequently, to remove the lid of the container, it is necessary torelease the vacuum. This is accomplished by providing a manuallyoperated relief valve which plugs into a hole in the lid. During thisoperation, air rushes into the container. Since the lid is normallyremoved in an area which is not totally sterile, there is a potentialsource of contamination. To minimize this effect, the relief valve ofthe invention incorporates a small filter that removes dust and mostother particles in the air. When the vacuum in the container is to berelieved, it is only necessary to pull on a tab attached to the valveflange to expose the valve opening and allow air to enter.

The container is constructed to withstand atmospheric pressure when avery high vacuum exists within the container. Nevertheless, with verylarge containers it is desirable to provide some additional supportingstructure as a safety precaution. Thus, as another feature of theinvention, an instrument basket positioned in the container is arrangedto support the lid. Further, the basket may be provided with acone-shaped projection extending upwardly from its bottom wall towardthe container lid, or such projection may be formed on either a lid orthe base and used with or without a basket. Thus, if the lid shouldcommence to buckle due to the pressure, the support cone will distributethe load and limit the inward movement.

SUMMARY OF THE DRAWINGS

For a more thorough understanding of the invention, refer now to thefollowing detailed description and drawings in which:

FIG. 1 is a perspective view of the overall container showing the lid ofthe container held in an open position;

FIG. 2 is a side elevational view of the container of FIG. 1, partiallycut away;

FIG. 3 is a side elevation of the container of FIG. 2 after the lid hasfallen into closed position;

FIG. 4 is a fragmentary, perspective view of one end of the containerbase;

FIG. 5 is a fragmentary, cross-sectional view of the container base ofFIG. 4 showing the lid and gasket positioned on the base, when the otherend of the lid is held in an open position;

FIG. 6 is a perspective, exploded view of the expandable chamberactuator and a fragment of the container base illustrating the manner inwhich the actuator is mounted on the base;

FIG. 7 is a view like FIG. 6 but with the actuator mounted on the baseand the chamber expanded;

FIG. 8 is a cross-sectional view of the expandable chamber showing theexpanded position of the chamber in phantom lines;

FIG. 9 is a cross-sectional view of the inlet valve of the expandablechamber showing the valve in closed position;

FIG. 10 is a fragmentary view of the container showing the actuator inside elevation on the container base and holding the lid open showingthe lid, base and gasket in cross-section;

FIG. 11 is a cross-sectional view of the gasket free form;

FIG. 12 is a cross-sectional view of the gasket mounted on a portion ofthe lid, also shown in cross-section;

FIG. 13 is a cross-sectional view of a portion of the lid, gasket andbase with the lid in closed position on the base;

FIG. 14 is a perspective view of the relief valve for the sterilizingcontainer;

FIG. 15 is a cross-sectional view of the valve of FIG. 14 installed inan opening in the container lid; and

FIG. 15b shows the valve with a vacuum in the container;

FIG. 16 is a perspective view on the upper side of the valve of FIG. 14showing the valve held in open position; and

FIG. 17 is a side view partially sectionalized showing a support cone inthe container basket illustrating the relation between the cone, basketcover, and the container lid.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 2, there is shown a container 10 havingaccess means or a lid 12 closing the open upper side of a base 14, witha gasket 16 carried by the lid and extending between the base and thelid. The container illustrated has a generally oval or racetrackconfiguration with the container lid having a somewhat dome-shape forstrength purposes. Other configurations, such as circular, could also beemployed. The upper portion of the lid is shaped to mate with recessesin the container base to facilitate stacking of the containers.

One end of the lid 12 is held open by an actuator 18 which is mounted onthe base 14. The actuator includes a bellows-like inflatable chamber 20which operates to release a lid at a desired point in an autoclavesterilizing cycle, allowing the lid to drop to the position shown inFIG. 3. FIG. 2 also shows a basket 22 and cover 23 within the containerfor holding items to be sterilized and to add support to the containerwhen a vacuum exists in it. One suitable material for the container ispolysulfone which is sold by Union Carbide Company.

The basket includes a plurality of holes 24 spaced around the lower sidewall of the basket, to permit sterilizing fluid to circulate and toallow air to escape. Also provided are a plurality of drain holes (notshown) in the basket bottom wall to permit condensation to drain fromthe basket. Referring to FIG. 5 it may be seen that the container base14 includes a bottom wall 14a which slopes downwardly and outwardly to ashoulder 14b leading to a peripheral groove 15. The bottom wall 14c ofthe groove 15 also slopes slightly downwardly in the outward directionto insure that condensation will flow through the drain holes in thebasket and drain holes 26 in the base, shown in FIG. 2. The periphery ofthe base includes an upwardly and outwardly sloping wall 14d terminatingin a generally horizontal flange 14e.

The base is formed with protuberances 14f to help guide the lid into itsproper position when it is being installed, as shown in FIG. 1, and tohelp prevent the lid from being improperly positioned on the base. FIG.5 shows the condition of the gasket, lid and base on the left end of thecontainer when the right end of the container is held in open positionas shown in FIG. 1.

Referring to FIGS. 6 and 7, it may be seen that the actuator 18 includesa plate-like member 28 having on its lower end a tab 30 which snaps intoa slot 32 formed in the base flange 14e on the right end of thecontainer as shown in FIG. 1. The actuator 18 further includes a pair ofprojections or posts 34 which extend outwardly from the plate 28. Theplate 28 is preferably formed as a one-piece plastic member formed in asingle molding operation.

Referring to FIG. 10, it may be seen that the tab 30 on the plate 28includes one or more detents 30a which require the tab 30 to be snappedinto position through the slot 32 in the flange 14e. This attachmentcoupled with the sides of the slot 32 in the somewhat horizontal wall 31on the plate 28 support the actuator plate in a position extendingupwardly approximately as shown in somewhat cantilever fashion. As canbe seen the post-like projections 34 on the support plate 28 connect tothe lid 12 by extending beneath the gasket 16 on the lid. Actually, withthe lid removed but with the support plate mounted on the base as shownin FIG. 10, the upper end of the support plate will move further thanshown in FIG. 10 towards the lid 12. This insures that the lid issecurely supported when the container is placed in an autoclave. Notefrom FIG. 10 that the support plate 28 extends inwardly towards the lidat its upper end as opposed to being completely vertical.

The support plate 28 provides a number of different characteristics.First, it should be sufficiently stiff and strong to support the lid andto provide the necessary reliability. In addition it should berelatively inexpensive so that it may be disposable. Molding the supportplate 28 in a single operation with its multiple functions greatlycontributes to this. In order to minimize the amount of materialrequired and yet attain the necessary stiffness and flexibility, theplate may be formed with a plurality of gussets 33 extending between thehorizontal wall 31 and the approximately vertical portions of the plate.Similarly, the edges of the upright portion may be thickened or ribbedto provide the necessary strength.

Referring to FIG. 8 as well as to FIG. 6, it may be seen that theexpandable chamber 20 is partially formed by a portion of the supportplate 28. More specifically, the upper portion of the support plate ismolded with a circular recess of two different diameters. The outerportion includes a cylindrical wall 36 and an annular wall 38, which isfurther connected to a smaller diameter cylindrical wall 40 which isjoined to a circular end wall 42. Together these walls form a cup-shapedrecess.

The expandable portion of the chamber 20 is formed by separatebellows-like element 44 molded of a plastic material similar to thatfrom which the plate 28 is molded but being of thinner cross-section andbeing more flexible. As can be seen the diaphragm 44 includes an outercylindrical wall 44a connected to an annular wall 44b which mate withthe walls 36 and 38 on the plate 28. These walls are joined by suitablemeans to form the expandible chamber 20. The diaphragm 44 furtherincludes short cylindrical wall sections 44c, 44d and 44e withconsecutively smaller diameters joined by connecting wall sections 44fand 44g. A central circular wall section 44h connected to thecylindrical wall 44e forms an end wall of the chamber. As can be seenfrom the phantom lines in FIG. 8, the diaphragm 44 assumes the positionindicated when the chamber is fully expanded. Note that the cylindricalwalls maintain their approximate configuration but are moved outwardlydue to the flexibility of the connecting annular wall sections 44f and44g.

The support plate 28 includes a tubular portion or nipple 46 which isformed integral with the wall 42 and projects into the chamber 20. Theinner end of the nipple is closed but a plurality of ports 48 in theside wall of the nipple connect the chamber 20 to the space around it.The nipple 46 tapers slightly inwardly to facilitate a single moldingoperation for the plate 28 and the ports 48 are formed at an angle tothe side wall of the nipple so that the ports may also be made duringthe molding operation. That is, the mold structure forming the interiorof the nipple and the ports may be withdrawn from the back side of theplate 28 at the completion of a molding operation. The material formingthe plate is somewhat flexible to permit such.

Positioned loosely over the nipple 46 is a cylindrical sleeve 50 made ofheat-shrinkable material. Although the sleeve is relatively confinedwithin the chamber, it may be more positively secured to the plate 42 bya small amount of adhesive on the end of the sleeve.

Referring to FIG. 11, the gasket 16 provides a critical functionrequiring very flexible resilient material formed in a specific design.The gasket 16 includes an upper generally cylindrical portion 16a havingon its upper edge a thickened bead adding to strength. The lower end ofthe portion 16a is connected to the upper leg 16b with a central sectionwhich takes a generally U-shape when installed on the lid. In additionto the leg 16b, this includes an annular wall 16c and a lower leg 16d,which in its free form shape extends somewhat downwardly. The outer endof the leg 16d is thickened to form a sealing bead 16e which leads to athin flap 16f which tapers to a feathered lower edge. Note that there isa rather acute angle 17 between the flap 16f and the back side of thebead portion 16e.

As may be seen from FIG. 12, the gasket 16 mounts on an outwardlyextending flange 12a formed on the lower end of the lid 12. The outerupper surface of the flange 12a is rounded as shown in FIG. 12 while thelower outer edge of the flange 12a is generally flat to mate with thegasket leg 16d when the lid is seated as shown in FIG. 13. The juncturebetween the flange 12a and the remainder of the lid 12 on the innersurface of the lid is smoothly rounded as can be seen from FIG. 12. Notealso that the vertical thickness of the flange 12a is slightly greaterthan the wall thickness at the outer extremity of the flange. As seenfrom FIG. 12, positioning the gasket on the lid flange causes the gasketleg 16d to move upwardly somewhat so that the walls 16b, 16c and 16dmove closer to a U-shape. The gasket assumes this configuration whereever it can hang free on the lid 12. In other words, referring to FIG.1, the gasket would assume the position shown in FIG. 12 throughout itsperiphery except that the gasket on the left end of the container willappear approximately as shown in FIG. 5 and the gasket on the right endof the container in the area of the support actuator 18 will be as shownin FIG. 10.

OPERATION

When the container is first placed in the autoclave, the actuator willbe in the position shown in FIGS. 1 and 10 holding the lid open and theexpandable chamber 20 will be in the position shown in FIG. 8. If theparticular autoclave cycle being used includes one or more preliminaryvacuum phases to withdraw air from the containers, no movement of theactuator will occur, since the port 48 and the valve for the inflatablechamber 20 are open and not covered by the sleeve 50. Any pressurechanges within the autoclave will be automatically applied to theinterior of the chamber as well. When a high temperature sterilizingfluid such as gas or steam is applied to the autoclave, the fluid flowsinto the interior of the container and through the open lid into theinterior of the basket through the ports 24, to displace the air andsterilize the container and the basket contents. Since the gasket 16 ispositioned on the lid 12 relatively loosely, it has been found that thesterilizing fluid will also effectively sterilize the lower surfaces ofthe lid and the surfaces of the gasket.

The sterilizing environment applied to the container will of course alsoenter the chamber 20 through the ports 48. The elevated temperature ofthe fluid will cause the sleeve-like valve element 50 to shrink andcover the ports 48, as shown in FIG. 9. The high temperature, highpressure fluid is thus captured in the chamber. No change however occursin the volume of the chamber during the remainder of the sterilizingphase, since temperature and pressure surrounding the chamber isessentially the same as that within it. Most autoclaves have some minorvariations in temperatures and pressures during the sterilizing phasebut such variations are not significant enough to cause the actuator toperform its actuating function. Thus, during the entire sterilizingphase, the lid of the container remains raised on one edge from the basesuch that fluid can flow freely into and out of the container. It isimportant that the lid be raised sufficiently to permit the sterilizingfluid to circulate freely and displace the air in the container.Preferably the lid should be raised at least a third of the height of adome-shaped lid. It is also important that the circulation holes 24 inthe basket be sized and spaced to permit the sterilizing fluid todisplace the air in the basket. Condensation drains from the basket 22through the holes in the bottom, and from the container through thedrain holes 26 in the container base 14.

At the completion of the sterilizing phase of the cycle, there is animmediate pressure drop. Temperature also drops but this is much moreslowly. As the pressure drops in the autoclave, the expandable chamber20 expands due to the fact that the pressure of the steam capturedwithin the chamber is greater than the pressure surrounding it. Thus,the bellows-like diaphragm 44 of the chamber 20 will move to theconfiguration shown in phantom lines in FIG. 8 and shown in solid linesin FIGS. 3 and 7. Since the central wall 44th of the diaphragm 44 isengaging the outer edge of the lid or its gasket, 16, as shown in FIG.10, the actuator plate 28 is urged to pivot in a clockwise directioninto the phantom line position shown in FIG. 10, this position alsobeing shown in FIG. 3. The actuator moves because the resistance tomovement provided by cantiliver mounting arrangement is much less thanthat of the lid 12. Thus, as the actuator moves, its projections orposts 34 are withdrawn from beneath the lid, allowing it to fall. Notefrom FIG. 8, that the wall 44h of the diaphragm 44 extends beyond thetip of the projections 34 when the bellows is fully expanded. Thisinsures that the lid will be released. With the lid released, theactuator will move back slightly somewhat towards the upper portion ofthe container lid, as shown in FIG. 3, but this movement is somewhatlimited while the expandable chamber is still expanded.

The lid falls into the proper position on the base and the gasket 16assumes the approximate position shown in FIG. 13. The sloping wall 14dhelps guide and lid into the peripheral groove 15 and the surfaces ofthe groove are smoothly curved to facilitate proper positioning of thelid. Correspondingly, the extremely flexible and resilient flap 16f onthe gasket insures a proper seal on a reliable basis. In a gravity-typeautoclave cycle wherein there is no final vacuum phase for withdrawingresidual sterilizing environment from the autoclave, a vacuum isnevertheless formed within the container as the residual environmentwithin the container cools and condenses, and as atmospheric pressure isintroduced into the autoclave surrounding the container. The pressuredifferential between the interior and the exterior of the container maybe quite small for a period of time in some situations such that it isimportant that a gasket prevent flow into the container at this time andthe feathered edge of the gasket performs this function. At the sametime, if the pressure within the container should be temporarily greaterthan the pressure on the outside of the container, the gasket featherededge will readily permit flow out of the container, thus acting like aone-way valve. As the pressure on the interior of the container dropsrelative to the exterior atmosphere pressure, the lid is drawn moretightly against the base thus compressing the gasket more. This causesthe bead 16e of the gasket to be further compressed between the lid andthe base, becoming the primary seal for the container.

If the container is utilized in an autoclave providing a final vacuumphase, the residual environment in the autoclave is quickly withdrawnand the residual environment within the container is likewise withdrawnpast the feathered edge of the gasket. When atmospheric pressure isintroduced into the autoclave, the feathered edge of the gasket preventsflow into the container; and a quickly produced pressure differentialbetween the interior and exterior of the container compresses the gasketgreatly so that the bead 16e seals the container more tightly.Consequently, the container contents are sealed in essentiallyatmosphere free sterile environment, until the contents are to be used.

When the container is removed from the autoclave, the actuator 18 may bemanually removed from the slot 32 in the container base and discarded.It is convenient to have a disposable type in a hospital environment,and the economics are such that this is a very practical approach.Alternatively, the actuator could be recycled by installing a newtemperature responsive value in the expandable chamber, or by employinga value of a type that would recycle automatically. As one example thenipple 46 could be made as a separate component and be removablyattached to the plate, and thus could be removed to permit replacementof the value element 50 and then reinstalled. Such an approach might bemost practical, if sterilization of the container and their contents isto be performed by specialists at a central location.

The container and its contents are then transported to a storage area orto the point where the contents are needed. In use, the container istypically moved to the general area of use, but the lid of the containeris actually removed somewhat remote from the actual operating or otheruse area in that the exterior of the container is contaminated duringstorage. When the lid is removed, the sterile basket on the interiorprotects the contents from falling dirt or other particles. The basketis carried to the actual area of use, and the cover on the basket isremoved to provide access to the instruments or other items within thebasket. This approach provides maximum sterility.

Relief Valve

Because of the high vacuum within the container, it is impossible toremove the container lid without relieving the vacuum. For this purpose,the relief valve 60 shown in FIGS. 1, 14, 15 and 16 is provided. As seenfrom FIG. 1, the relief valve is located in the top wall of the lid 12;however, it should be recognized that such a valve can be placed inother locations as well. Referring to FIG. 14, the valve is made offlexible resilient material as a one-piece member except for an innerfilter 62. The valve includes a generally tubular projection or plug 64which is open on its lower end and enclosed by an enlarged resilientflange 66 on its upper or outer end. A passage 68 through the projection64 opens to a port 70 in a side wall of the projection immediatelybeneath the flange 66.

In use, the projection 64 is inserted through an opening in the lid 12.This operation is performed with the rigid, metal foam filter removed.The filter 62 is then installed in the lower end of the plug portion 64as shown in FIG. 15. This not only secures the filter within the plugextending across the passage, but also helps pull the valve in a sealedcondition in combination with a ring 65 on the exterior of the plug. Thenormal position of the valve when the container is not vacuumized is asshown in FIG. 15 with the annular edge 66a of the flange 66 against theouter surface of the lid thus preventing flow into the container throughthe port 70 and passage 68.

When the container lid 12 moves to its closed position, the valve 60prevents air flow into the container; and as a vacuum is formed withinthe container, the exterior pressure forces most of the lower surface ofthe valve flange 66 against the lid. The annular relief groove 69 in theupper surface of the flange 66 and the annular groove 67 in the lowersurface adjacent the plug 64 enable the flange to flatten readily. Inaddition, the thin upper wall 66b of the flange covering the end of thepassage 68 is drawn inwardly because of the vacuum. This providesvisible indication to an observer that a vacuum condition exists in aparticular container.

When the vacuum is to be released to enable the container lid to bewithdrawn, a tab 74 is manually pulled to lift the edge of the flange 66away from the lid so that air may flow into the port 70 and through thepassage 68 in the valve. If desired, the tab may be hooked on a tabholder 76 as shown in FIG. 16. This may be convenient in that the filter60 is so fine that it will take several seconds for the pressure toequalize in a large container. All of the air entering the containermust of course pass through the filter 62. Consequently, even though theentering air has not been subjected to high temperature sterilization, ahigh percentage of the dust, lint and other particles within the air areremoved as the air passes through the filter. Once the containerinterior and exterior equalize, the lid can be lifted off of the base toprovide access to the inner gasket.

Lid Support

Although the container 10 is constructed to withstand a high vacuum, ithas been found desirable to provide further mechanical support for largecontainers. A preferred approach for providing such support isillustrated in FIG. 17. The basket cover 23, which is supported on itsperiphery by the basket base 22, is dimensioned so that its uppersurface mates with the lower surface of the lid 12; and normally with acontainer lid tightly closed on a container base, the lid would beslightly spaced from the inner basket. However, if an overstressedcondition should occur, such that the lid 12 should begin to buckle, itwill engage the upper surface of the basket cover 23 to be supportedthereby.

Further, with particularly large containers, the lower portion of theinner basket 22 is provided with an upwardly extending cone-shapedprojection 78 that terminates near the cover 23 of the basket. Theperiphery of the basket cover 23 rests on the basket base 22, but italso engages or comes close to engaging the upper end of the supportcone. The container lid 12 is formed with recesses that arecomplementarily receives in the basket cover. Thus in the overstressedsituation the basket cover will reset upon the upper end of the supportcone 78 on the basket base, thus preventing collapse of the lid. Ofcourse, a suitable support may be provided as a separated element, orattached to either the container lid or base, and used without a basket;or used with a modified basket which would fit with a support.

The operation of two different autoclave cycles is briefly discussedabove. It is believed that this is sufficient for purposes ofunderstanding the invention. However, if further information is desired,reference may be had to the surface mentioned U.S. patent applicationSer. No. 895,239 or Ser. No. 821,042, both of which discuss such cyclesin greater details and include a time, temperature and pressure graph ofsuch operations.

Although the container is primarily designed for use with a steam or gasautoclave sterilizing cycle, it should be understood that it is alsovery useful with other sterilizing techniques. With microwavesterilizing, the container lid may be positioned on the container basein a lightly closed condition. As the contents are heated, any pressureincrease within the container may vent from the container past theflexible gasket. When the container cools, a vacuum will be formed inthe container, automatically pulling the lid more tightly closed on thecontainer base.

With radiation sterilizing, which does not rely on heat, the containerlid is placed on the base in a lightly closed position, and thecontainer is then subjected to a vacuum to withdraw air from thecontainer past the flexible gasket. When pressure around the containeris again allowed to increase, the lid will be tightly compressed on thebase, since the gasket will prevent a pressure increase in thecontainer. The container is then subjected to radiation, leaving thecontainer contents sterilized and sealed in an essentially atmospherefree environment.

The container may be used for a wide variety of items in addition tosurgical instruments. If it is used solely for towels, bandages, andother such somewhat bulky items, it may be convenient to invert thecontainer so that the lid becomes the base, and not use the basket. Theside walls of the inverted lid will hold items like towels more easilythan will a flat base. The expandable chamber actuator would function inthe same manner as described above. Once the container is closed, itcould of course be returned to original position for storage and ease ofhandling. In the inverted position there would be no provision fordrainage with the container illustrated; but there would be no drainagewith towels. If desired the relief valve in the inverted lid may bemodified to be open during the sterilizing phase and then automaticallyclosed in response to temperature. Such a valve is described in theabove application, Ser. No. 923,359. In addition to being a drain forcondensate, a valve of this type would more importantly allow air todrain from the container as the steam or other sterilizing fluid isapplied.

We claim:
 1. Apparatus for containing items while being sterilized andstored comprising:means forming a container including means providingaccess to the container interior; support means holding said accessmeans open; means attached to said support means forming an expandablechamber positioned so that expansion of said chamber will move saidsupport means to release said access means and permit it to close; and arelief valve in said container for relieving a vacuum within saidcontainer to permit the access means to be opened, said relief valveincluding a filter therein arranged so that any air entering thecontainer through the relief valve must pass through said filter; saidrelief valve comprises a resilient member having a tubular plug which isinserted into a hole in said container and includes an outer flangesecured to said plug and sealed against the outer surface of saidcontainer, said tubular plug having a passage open at one end into theinterior of said container and open at its other end through a port inthe side wall of the said tubular plug adjacent said flange providingcommunication with the exterior of the chamber when the valve flangeadjacent said port is partially pulled away from the container.
 2. Theapparatus of claim 1 wherein said filter comprises a rigid metal porousmaterial positioned in the inner end of said plug so that all airentering the container must pass through said filter and the size ofsaid filter is sufficient to help hold said plug in said access meanswith said flange held tightly against the container.
 3. The apparatus ofclaim 1 wherein said valve flange includes an outwardly extending tab tobe manually grasped for facilitating opening of the valve.
 4. Theapparatus of claim 3 wherein said valve flange includes an outwardlyextending tab holder to which said tab may be attached for manuallyholding the flange in the valve open position.
 5. The apparatus of claim1 including an outwardly extending ring formed on said plug spaced fromsaid flange and adjacent to an inner surface of said container to helphold the valve plug in said hole with said flange sealed against saidcontainer outer surface.
 6. A container comprising:a pair of memberswhich cooperate to form an enclosure; and a gasket positioned betweenthe members, said gasket being formed of flexible resilient material andincluding a U-shaped portion which fits somewhat loosely over aperipheral flange formed on one of said members, said flange forming theouter most portion of said one member and a cylindrical portion attachedto the open end of one leg of said U-shaped portion and surrounding theexterior of said one member adjacent said flange, said gasket furtherincluding an elongated annular flap which is secured to the open end ofthe other leg of said U-shaped portion and tapers to a thin featherededge for mating with the other of said members to prevent fluid flowinto the container when only the weight of the members compresses thegasket while still permitting flow out of the container when thepressure inside the container is greater than that outside thecontainer, the junction between said annular flap and said other leg ofthe U-shaped portion being enlarged to form a bead to be compressedbetween the members to form a seal spaced inwardly from said featherededge when pressure outside the container increases with respect to thecontainer interior, said flap being constructed so that it is positionedto be compressed between said U-shaped portion and said other one ofsaid members.
 7. The apparatus of claim 6 wherein said members are abase and a lid and said flange is formed on said lid and the gasket iscarried by the lid, and said flap is sufficiently flexible such thatwhen one edge of the lid is raised from the base a few inches and thenreleased to fall onto the base, a seal is formed by said feathered edgeto prevent flow into the container.
 8. Apparatus comprising a containerhaving a wall with a hole extending therethrough, a resilient valvemember having a tubular portion extending through said hole, saidportion having a closed end and an open end and having a flange adjacentthe closed end of the tubular portion, a passage through said tubularportion extending from the open end to a port in the sidewall of thetubular portion adjacent said flange, a filter positioned in the openend of said tubular portion causing that end of the tubular portion tobulge outwardly so that its outer diameter is larger than the hole insaid wall, the filter being located such that the bulging end helps holdthe valve member in said hole with said flange in engagement with thesurface of the wall surrounding said hole thereby preventing fluid flowthrough the passage, said passage being openable by manually pulling aportion of the flange adjacent said port away from said wall to uncoverthe port and permit flow through the passage.
 9. The apparatus of claim8 including a tab attached to said flange for facilitating pulling theflange into position to uncover the port, and a tab holder attached tosaid flange for holding the tab in said position.